Functionalization of Fe3O4 nanoparticles with propylaminopyridine and its use as an efficient catalyst in the synthesis of novel 4,8-dihydro-1H-pyrimido[1,2-a]pyrimidines

In this study, at first, 2-amino-1,4-dihydropyrimidine was synthesized by the reaction of guanidine hydrochloride, 4-methybenzaldehyde and ethyl benzoylacetate in the presence of sodium hydrogencarbonate as catalyst. Also, Fe3O4 nanoparticles were synthesized and functionalized via sequential reactions with chloropropyl(trimethoxy)silane and 2-aminopyridine. The resulting nanoparticles were used as environmentally benign magnetic nano-catalyst for the synthesis of some novel ethyl 2-amino-4-aryl-8-(4-methylphenyl)-3-cyano-6-phenyl-8,4-dihydro-1H-pyrimido[1,2-a]pyrimidine-7-carboxylate derivatives via a one-pot reaction of 2-amino-1,4-dihydropyrimidine, an aromatic aldehyde, and malononitrile. All the reaction steps are performed under ultrasound irradiation. Simple operation, high reaction yields, reusability of the catalyst for several times, short reaction times and easy separation of catalyst are the key advantages of using this catalyst.